CN108233328B - A kind of short-circuit protection method of linear soft-start circuit - Google Patents
A kind of short-circuit protection method of linear soft-start circuit Download PDFInfo
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- CN108233328B CN108233328B CN201810173214.7A CN201810173214A CN108233328B CN 108233328 B CN108233328 B CN 108233328B CN 201810173214 A CN201810173214 A CN 201810173214A CN 108233328 B CN108233328 B CN 108233328B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
- H02H3/08—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection responsive to excess current
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- Protection Of Static Devices (AREA)
Abstract
The invention discloses a kind of short-circuit protection methods of linear soft-start circuit, comprising: the electric current and output voltage for obtaining circuit obtain current detection value and voltage detecting value by signal condition；The minimum reference value V of short-circuit protection comparator is setr, wherein VrGreater than 0；Current detection value and voltage detecting value are separately input to two input terminals of short-circuit protection comparator；When voltage detecting value is greater than minimum reference value VrWhen, using voltage detecting value as a reference value of short-circuit protection comparator；Short-circuit protection comparator is compared received current detection value with the size of its a reference value；Identify short-circuit condition, triggering short-circuit protection movement.The short trouble of linear soft-start circuit can be effectively protected in method provided by the invention.
Description
Technical field
The present invention relates to circuit protection technical field more particularly to a kind of short-circuit protection methods of linear soft-start circuit.
Background technique
There are the equipment that relatively high power fluctuates, supply sides often to access for high-power transmitter for pulsed operation etc.
The storage capacitor of large capacity, to provide pulse power.Simultaneously to avoid introducing the impact of capacitor bring starup current, frequently with
A kind of linear soft-start circuit based on field-effect tube, as shown in Figure 1.The circuit accesses field effect between power supply Vdc and capacitor C
Should pipe Q by opening voltage to the injection of the grid of Q is slow it being connected slowly when powering on achieve the effect that limiting capacitance charging current.
For the short-circuit protection of foregoing circuit load-side, the prior art is only by the high current information after short circuit come to short circuit
State is identified, then executes protection act again.Usual way is will to export electric current to be compared with fixed preset value,
Field-effect tube is turned off when electric current is more than preset value.In order to eliminate the erroneous judgement to pulse current in transient process, short-circuit protection
Preset value is usually very big.If load is short-circuit before powering on, due to the cut-off current characteristics of field-effect tube delay startup, it will limit and power on
When short circuit current rising, greatly postponement electric current reaches time of preset value and trigger protection.Field-effect tube during this
Work can persistently subject very big power in linear zone, be easy to damage because of overpower.
For the short-circuit protection of this linear soft-start circuit, the prior art is only short to load when powering on rear steady operation
Road is effective, and can not protect to the load short circuits failure that there is before powering on, and there are limitations.
Summary of the invention
The technical problems to be solved by the present invention are: in view of the above-mentioned problems existing in the prior art, proposing a kind of short circuit
The short trouble of above-mentioned linear soft-start circuit can be effectively protected in the method for protection.
A kind of short-circuit protection method of linear soft-start circuit provided by the invention, comprising:
The electric current and output voltage for obtaining circuit, obtain current detection value and voltage detecting value by signal condition；
The minimum reference value V of short-circuit protection comparator is setr, wherein VrGreater than 0；
Current detection value and voltage detecting value are separately input to two input terminals of short-circuit protection comparator；
When voltage detecting value is greater than minimum reference value VrWhen, using voltage detecting value as the benchmark of short-circuit protection comparator
Value；
Short-circuit protection comparator is compared received current detection value with the size of its a reference value；
Identify short-circuit condition, triggering short-circuit protection movement.
Further, current detection value and voltage detecting value are separately input to the positive and negative input terminal of short-circuit protection comparator；When
When the output of short-circuit protection comparator is high, it is identified as short-circuit condition, starting short-circuit protection movement.
Further, minimum reference value VrCurrent detection value corresponding to the maximum short circuit current being switched on when according to short circuit is set
It is fixed.
Further, the conditioning process of electric current and output voltage are as follows: amplification factor of the electric current in circuit delay startup is A1,
Amplification factor A2, A1 > A2 when circuit works normally；The amplification factor of output voltage is A3, and wherein the setting of A2 meets circuit
The corresponding current detection value of maximum surge current is less than minimum output voltage corresponding electricity when circuit works normally when normal work
Press detected value.
Further, the selection of A1 and A2 is selected by the control of voltage detecting value when voltage detecting value reaches setting value
A2。
Further, A3 is short-circuit protection comparator supply voltage according to the corresponding voltage detecting value of circuit maximum output voltage
Half be arranged.
Further, A1 is twice of A2.
Further, setting value is the half of the corresponding voltage detecting value of normal output voltage.
By using above technical solution, the beneficial effects of the present invention are: short-circuit protection method of the invention, shortens
The recognition time of linear soft-start circuit short trouble, so that no matter short trouble occurs to carry out effectively in which kind of situation
Protection, compensate for the deficiencies in the prior art, improve the reliability of circuit.
Detailed description of the invention
Examples of the present invention will be described by way of reference to the accompanying drawings, in which:
Fig. 1 is the schematic diagram of linear soft-start circuit；
The circuit diagram of the short-circuit protection method of Fig. 2 to realize the present invention；
Fig. 3 is simulation waveform when normally starting with the consistent circuit of exemplary embodiment of the present invention；
Fig. 4 is the simulation waveform of short-circuit protection when powering on the consistent short circuit of exemplary embodiment of the present invention；
Fig. 5 is the simulation waveform of short-circuit protection when working normally with the consistent circuit of exemplary embodiment of the present invention.
Specific embodiment
All features disclosed in this specification or disclosed all methods or in the process the step of, in addition to mutually exclusive
Feature and/or step other than, can combine in any way.
Any feature disclosed in this specification unless specifically stated can be equivalent or with similar purpose by other
Alternative features are replaced.That is, unless specifically stated, each feature is an example in a series of equivalent or similar characteristics
?.
Short-circuit protection method of the invention is accelerated to protect based on the recognition time for shortening short trouble, reduces linearly slow open
Dynamic device bears the time of power stress when load short circuits are opened, and will not damage.
The present invention is to shorten short trouble recognition time, is detecting except electric current, is increasing the detection to output voltage, and
Using the latter as a reference value of short-circuit protection comparator, short-circuit condition is quickly identified by the comparison of the two.Specifically
It is as follows:
1) electric current and output voltage for obtaining circuit respectively, obtain current detection value and voltage detecting by signal condition
Value；And current detection value and voltage detecting value are separately input to two input terminals of short-circuit protection comparator.
2) it is greater than 0 minimum reference value V for the setting of short-circuit protection comparatorr, avoid occurring accidentally protecting when booting.Some
In embodiment, minimum reference value VrCurrent detection value corresponding to the maximum short circuit current being switched on when according to short circuit is set.
3) when voltage detecting value is greater than minimum reference value, make it as a reference value of short-circuit protection comparator.
In some embodiments, increase the amplification factor of electric current in the circuit delay startup stage.
The circuit diagram of the short-circuit protection method of Fig. 2 to realize the present invention.As shown in Fig. 2, A3 is putting for output voltage
Big multiple, output are voltage detecting value, can be compared by the corresponding voltage detecting value of circuit maximum output voltage for short-circuit protection
The half of device supply voltage is arranged.In a specific embodiment, circuit maximum output voltage is 300V, and short-circuit protection compares
Device supply voltage is 12V, therefore sets A3 as 0.02.
Current amplification factor when A1 is circuit delay startup, current amplification factor when A2 is normal work, A1 > A2, it
Output be current detection value.A2 need to meet maximum surge current corresponding current detection value when circuit works normally and be less than
Minimum output voltage corresponding voltage detecting value when circuit works normally.In a specific embodiment, when circuit works normally
Minimum voltage is 240V, and by the amplification factor of A3 in above-mentioned specific embodiment, corresponding voltage detecting value is 4.8V.Circuit is just
Often maximum surge current is 100A when work, therefore A2 need to may be set to 0.04 less than 0.048.In some embodiments, A1 is desirable
It is twice of A2, is set as 0.08.
In some embodiments, current detection value is separately input to the positive and negative of short-circuit protection comparator U with voltage detecting value
To input terminal.Switch K2 will be connected when U output is high, turns off Q.
VrIt is the minimum reference value of setting, is connected by diode with voltage detecting value.VrThe maximum being switched on when according to short circuit
Current detection value corresponding to short circuit current is set.In a specific embodiment, the maximum being switched on when the short circuit of permission is short
Road electric current can set V by the amplification factor of A1 in above-mentioned specific embodiment for 20ArFor 1.6V.
Switch K1 by voltage detecting value control, to select different current amplification factors.In circuit delay startup process
Middle voltage detecting value is small compared with when working normally, and selects A1 by K1 at this time；After working normally, A2 is selected.It is specific real at one
It applies in example, A1, A2 switching moment, may be set to the half that voltage detecting value is the corresponding voltage detecting value of normal output voltage
When.In a specific embodiment, normal output voltage 270V, corresponding voltage detecting value is 5.4V, then when K1 is acted
It carves corresponding voltage detecting value and output voltage is respectively 2.7V and 135V.
Fig. 3 is simulation waveform when normally starting with the consistent circuit of exemplary embodiment of the present invention.Such as Fig. 3 institute
Show, upper coordinate system is voltage and current waveform, and lower coordinate system is corresponding voltage detecting value and current detection value waveform.Starting
Afterwards, voltage and current is all started from scratch rising, and voltage tends towards stability after reaching normal output voltage (such as 270V), and electric current reaches most
It is then reduced rapidly after big charging current.Due to the presence of minimum reference value, voltage detecting value is from VrIt begins to ramp up, current detection value
Then follow current is started from scratch growth.When voltage detecting value rises to setting value (such as 2.7V) with output voltage, Current amplifier
Multiple is reduced to A2 by A1, and amplification factor switching has occurred.
Fig. 4 is the simulation waveform of short-circuit protection when powering on the consistent short circuit of exemplary embodiment of the present invention.
Circuit during delay startup, at this time voltage detecting value it is lower, correspondingly, a reference value of short-circuit protection comparator be also at it is lower
It is horizontal.Due to being set with minimum reference value Vr, so a reference value of short-circuit protection comparator will not be less than VrValue.Normally starting
When, due to the metering function of linear soft-start circuit, current detection value increases since 0；The a reference value of short-circuit protection comparator
As output voltage rises from VrStart to increase: this makes the former be consistently less than the latter, until entering normal condition, terminates slow open
It is dynamic.
When load short circuits failure, current detection value still increases since 0, but output voltage is short-circuited leads to short-circuit guarantor
The a reference value of shield comparator is limited in V alwaysr.When short circuit current rises to the maximum permissible value of setting, current detection value
Just it is equal to Vr, short-circuit protection comparator quickly recognizes short-circuit condition, and then trigger protection acts.Simultaneously as this stage
Current amplification factor is big compared with when working normally, and the electric current at corresponding protection moment is smaller, not only shortens linear delay startup device and holds
By the time of power, maximum power stress is also reduced.
As shown in figure 4, the coordinate system of the top is protection signal waveform.Since output is short-circuit before powering on, electricity
Pressure is always 0V, and voltage detecting value is then always Vr.Electric current and its detected value all rapid increases, when current detection value reaches VrWhen
It carves, trigger protection movement.
Fig. 5 is the simulation waveform of short-circuit protection when working normally with the consistent circuit of exemplary embodiment of the present invention.
When circuit is in normal work, voltage detecting value is higher at this time, a reference value and current detecting as short-circuit protection comparator
Value is compared, and can eliminate the erroneous judgement to pulse current in transient process.When load short circuits failure occurs, output voltage meeting
It drags down, so that a reference value of short-circuit protection comparator reduces therewith；Short circuit current can be promoted simultaneously, so that current detection value is therewith
Increase.The former reduces, and the latter increases, and the two, which crosses rapidly, makes short-circuit protection comparator recognize short-circuit condition, and then triggers and protect
Shield movement.
As shown in figure 5, suddenly-applied short circuit when circuit works normally, output voltage and its voltage detecting value rapid decrease, electric current
And its current detection value rapid increase.When voltage detecting value is decreased below setting value (such as 2.7V) with output voltage, electric current
Amplification factor switching, current detection value increases suddenly, and quickly crosses with voltage detecting value, trigger protection movement.
The invention is not limited to specific embodiments above-mentioned.The present invention, which expands to, any in the present specification to be disclosed
New feature or any new combination, and disclose any new method or process the step of or any new combination.
Claims (8)
1. a kind of short-circuit protection method of linear soft-start circuit characterized by comprising
The electric current and output voltage for obtaining circuit, obtain current detection value and voltage detecting value by signal condition；
The minimum reference value V of short-circuit protection comparator is setr, wherein VrGreater than 0；
Current detection value and voltage detecting value are separately input to two input terminals of short-circuit protection comparator；
When voltage detecting value is greater than minimum reference value VrWhen, using voltage detecting value as a reference value of short-circuit protection comparator；
Short-circuit protection comparator is compared received current detection value with the size of its a reference value；
Identify short-circuit condition, triggering short-circuit protection movement.
2. a kind of short-circuit protection method of linear soft-start circuit according to claim 1, which is characterized in that current detecting
Value and voltage detecting value are separately input to the positive and negative input terminal of short-circuit protection comparator；When the output of short-circuit protection comparator is
Gao Shi is identified as short-circuit condition, triggering short-circuit protection movement.
3. a kind of short-circuit protection method of linear soft-start circuit according to claim 1 or 2, which is characterized in that minimum
A reference value VrCurrent detection value corresponding to the maximum allowable short circuit current being switched on when according to short circuit is set.
4. a kind of short-circuit protection method of linear soft-start circuit according to claim 1, which is characterized in that electric current and defeated
The conditioning process of voltage out are as follows: amplification factor of the electric current in circuit linearity delay startup is A1, putting when circuit works normally
Big multiple A2, A1 > A2；The amplification factor of output voltage is A3, and wherein the setting of A2 meets maximum impulse when circuit works normally
The corresponding current detection value of electric current is less than minimum output voltage corresponding voltage detecting value when circuit works normally.
5. a kind of short-circuit protection method of linear soft-start circuit according to claim 4, which is characterized in that A1's and A2
Selection is selected A2 when voltage detecting value reaches setting value by the control of voltage detecting value.
6. a kind of short-circuit protection method of linear soft-start circuit according to claim 4, which is characterized in that A3 is according to electricity
Maximum output voltage corresponding voltage detecting value in road is the half of short-circuit protection comparator supply voltage to be arranged.
7. according to a kind of described in any item short-circuit protection methods of linear soft-start circuit of claim 4-6, which is characterized in that
A1 is twice of A2.
8. a kind of short-circuit protection method of linear soft-start circuit according to claim 5, which is characterized in that setting value is
The half of the corresponding voltage detecting value of normal output voltage.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810173214.7A CN108233328B (en) | 2018-03-02 | 2018-03-02 | A kind of short-circuit protection method of linear soft-start circuit |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201810173214.7A CN108233328B (en) | 2018-03-02 | 2018-03-02 | A kind of short-circuit protection method of linear soft-start circuit |
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| Publication Number | Publication Date |
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| CN108233328A CN108233328A (en) | 2018-06-29 |
| CN108233328B true CN108233328B (en) | 2019-04-23 |
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| CN201810173214.7A Active CN108233328B (en) | 2018-03-02 | 2018-03-02 | A kind of short-circuit protection method of linear soft-start circuit |
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2438255Y (en) * | 2000-08-10 | 2001-07-04 | 北京通力环电气有限公司 | HF switch power output short-circuit current-limiting controller |
| CN1511376A (en) * | 2001-05-25 | 2004-07-07 | 矢崎总业株式会社 | Overcurrent detection and protection apparatus for switching element |
| CN2850088Y (en) * | 2005-10-31 | 2006-12-20 | 崇贸科技股份有限公司 | Overcurrent level adjustable overpower protector |
| CN1950981A (en) * | 2004-05-06 | 2007-04-18 | 罗姆股份有限公司 | Overcurrent detecting circuit and power supply device provided with it |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP4223331B2 (en) * | 2003-06-13 | 2009-02-12 | 株式会社日立製作所 | Protection device for power control semiconductor element and power conversion device including the same |
-
2018
- 2018-03-02 CN CN201810173214.7A patent/CN108233328B/en active Active
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2438255Y (en) * | 2000-08-10 | 2001-07-04 | 北京通力环电气有限公司 | HF switch power output short-circuit current-limiting controller |
| CN1511376A (en) * | 2001-05-25 | 2004-07-07 | 矢崎总业株式会社 | Overcurrent detection and protection apparatus for switching element |
| CN1950981A (en) * | 2004-05-06 | 2007-04-18 | 罗姆股份有限公司 | Overcurrent detecting circuit and power supply device provided with it |
| CN2850088Y (en) * | 2005-10-31 | 2006-12-20 | 崇贸科技股份有限公司 | Overcurrent level adjustable overpower protector |
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| Publication number | Publication date |
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| CN108233328A (en) | 2018-06-29 |
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